Mineralization of SF₆ and NF₃ fluorinated compounds for greenhouse gas abatement by oxalates

Fluorinated compounds (FCs) such as sulfur hexafluoride (SF₆) and nitrogen trifluoride (NF₃) have garnered attention due to their environmental impact. This study investigates the mineralization and removal of two potent FCs: SF₆ and NF₃. The results confirm that utilizing various oxalate salts leads to the formation of corresponding metallic fluorides: lithium fluoride (LiF), sodium fluoride (NaF), and potassium fluoride (KF), validating the occurrence of mineralization reactions. Among the oxalate salts, sodium oxalate demonstrates the highest mineralization efficiency in both SF₆ and NF₃ removal. Real-time Fourier transform infrared spectroscopy (FT-IR) gas-phase analysis confirms rapid and complete gas removal within a short reaction time using the selected oxalate salts. Meticulous mass balance calculations revealed that oxalates (LiF, NaF, and KF) yielded sulfur (S) at rates of 92.09%, 91.85%, and 84.98% following SF₆ mineralization. Additionally, the conversion rates of oxalates to the corresponding metallic fluorides (LiF, NaF, and KF) after SF₆ mineralization were 98.18%, 95.82%, and 95.21%, respectively. Similarly, after NF₃ mineralization, these conversion rates stood at 92.18%, 90.67%, and 90.02%, respectively. The removal efficiencies for SF₆ (1000 ppm) were 4.98, 12.01, and 7.23 L/g, while those for NF₃ (1000 ppm) were 14.1, 12.6, and 11.7 L/g, respectively. Notably, sodium oxalate exhibits superior effectiveness, achieving 100% SF₆ conversion within 30 min and 100% NF₃ conversion within 50 min. This work underscores the potential of oxalate mineralization as a promising strategy for efficient and rapid removal of potent fluorinated compounds, paving the way for environmentally benign FC remediation techniques with broader implications for sustainable gas treatment technologies.